The present invention relates to an electrochemical process for simultaneously stripping diverse coatings from a metal substrate and, more particularly to the removal of MCrAlY and aluminide coatings from a base metal.
Elements of gas turbine engines are protected from high oxidation and corrosion by coating the base metals with a protective coating. Gas turbine engine combustor float wall elements are protected from high temperature oxidation and corrosion with two types of coatings. The first coating is a coating of MCrAlY on the inside surface of a combustor float wall and an aluminide coating on the outside surface of the float wall. To date, the repair sequence for such elements requires the removal of coatings from the base metal. The current process involves separate stripping techniques for the two coatings. The MCrAlY coating is removed either by soaking the parts in a high concentrated hot hydrochloric acid solution or by water jet blasting. The aluminide coating is removed by stripping in nitric acid. These processes are difficult to control, are hazardous, and extremely labor intensive.
It is clear that indeed remains for an approved process for stripping diverse coatings from a metal substrate.
It is therefore the primary object of the present invention to provide such a process.
Other objects and advantages will appear hereinbelow.